crater experiment: do not promote function calls in const/static items #148952

RalfJung · 2025-11-14T19:45:00Z

This repeats the experiment from #122819. Back then, not even cargo built; since then, time-rs/time#704 has landed so maybe we get a bit further this time.

See #124328 for context.

RalfJung · 2025-11-14T19:46:47Z

@bors try

crater experiment: do not promote function calls in const/static items

RalfJung · 2025-11-14T20:15:58Z

Lol, this time we can't build clippy.^^ owo-colors fails.

This seems to have been fixed a year ago (owo-colors/owo-colors#131), but we depend on an ancient version of owo-colors via prettydiff. A newer prettydiff is available that would fix that, but the latest ui_test depends on an old prettydiff.

rust-bors · 2025-11-14T22:03:44Z

☀️ Try build successful (CI)
Build commit: 943e220 (943e2200e35c3825486c4671b6cab0107a07f8c1, parent: 42f4793e5a514858221b07ac379029d90353913e)

RalfJung · 2025-11-14T22:25:25Z

@craterbot check

craterbot · 2025-11-14T22:25:55Z

👌 Experiment pr-148952 created and queued.
🤖 Automatically detected try build 943e220
🔍 You can check out the queue and this experiment's details.

ℹ️ Crater is a tool to run experiments across parts of the Rust ecosystem. Learn more

rust-log-analyzer · 2025-11-16T14:56:09Z

The job aarch64-gnu-llvm-20-2 failed! Check out the build log: (web) (plain enhanced) (plain)

Click to see the possible cause of the failure (guessed by this bot)

   Compiling y v0.1.0 (/checkout/compiler/rustc_codegen_cranelift/build_system)
error[E0716]: temporary value dropped while borrowed
  --> compiler/rustc_codegen_cranelift/build_system/abi_cafe.rs:14:52
   |
14 | static ABI_CAFE: CargoProject = CargoProject::new(&ABI_CAFE_REPO.source_dir(), "abi_cafe_target");
   |                                 -------------------^^^^^^^^^^^^^^^^^^^^^^^^^^--------------------
   |                                 |                  |                                            |
   |                                 |                  |                                            temporary value is freed at the end of this statement
   |                                 |                  creates a temporary value which is freed while still in use
   |                                 argument requires that borrow lasts for `'static`

error[E0716]: temporary value dropped while borrowed
 --> compiler/rustc_codegen_cranelift/build_system/build_backend.rs:9:51
  |
9 | static CG_CLIF: CargoProject = CargoProject::new(&RelPath::source("."), "cg_clif");
  |                                -------------------^^^^^^^^^^^^^^^^^^^^------------
  |                                |                  |                              |
  |                                |                  |                              temporary value is freed at the end of this statement
  |                                |                  creates a temporary value which is freed while still in use
  |                                argument requires that borrow lasts for `'static`

error[E0716]: temporary value dropped while borrowed
   --> compiler/rustc_codegen_cranelift/build_system/build_sysroot.rs:143:24
    |
143 |     CargoProject::new(&RelPath::build("stdlib/library/sysroot"), "stdlib_target");
    |     -------------------^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^------------------
    |     |                  |                                                        |
    |     |                  |                                                        temporary value is freed at the end of this statement
    |     |                  creates a temporary value which is freed while still in use
    |     argument requires that borrow lasts for `'static`

error[E0716]: temporary value dropped while borrowed
   --> compiler/rustc_codegen_cranelift/build_system/tests.rs:132:48
    |
132 | static RAND: CargoProject = CargoProject::new(&RAND_REPO.source_dir(), "rand_target");
    |                             -------------------^^^^^^^^^^^^^^^^^^^^^^----------------
    |                             |                  |                                    |
    |                             |                  |                                    temporary value is freed at the end of this statement
    |                             |                  creates a temporary value which is freed while still in use
    |                             argument requires that borrow lasts for `'static`

error[E0716]: temporary value dropped while borrowed
   --> compiler/rustc_codegen_cranelift/build_system/tests.rs:142:49
    |
142 | static REGEX: CargoProject = CargoProject::new(&REGEX_REPO.source_dir(), "regex_target");
    |                              -------------------^^^^^^^^^^^^^^^^^^^^^^^-----------------
    |                              |                  |                                      |
    |                              |                  |                                      temporary value is freed at the end of this statement
    |                              |                  creates a temporary value which is freed while still in use
    |                              argument requires that borrow lasts for `'static`

For more information about this error, try `rustc --explain E0716`.
[RUSTC-TIMING] y test:false 0.449
error: could not compile `y` (bin "y") due to 5 previous errors
Bootstrap failed while executing `--stage 2 test --skip tests --skip coverage-map --skip coverage-run --skip library --skip tidyselftest`
Command `/checkout/obj/build/aarch64-unknown-linux-gnu/stage0/bin/cargo run --target aarch64-unknown-linux-gnu -Zbinary-dep-depinfo -j 4 -Zroot-dir=/checkout --locked --color always --release --manifest-path /checkout/compiler/rustc_codegen_cranelift/build_system/Cargo.toml -- test --download-dir /checkout/obj/build/cg_clif_download --out-dir /checkout/obj/build/aarch64-unknown-linux-gnu/stage2-codegen/cg_clif --no-unstable-features --use-backend cranelift --sysroot llvm --skip-test testsuite.extended_sysroot [workdir=/checkout/compiler/rustc_codegen_cranelift]` failed with exit code 101
Created at: src/bootstrap/src/core/build_steps/test.rs:3717:25
Executed at: src/bootstrap/src/core/build_steps/test.rs:3762:26

Command has failed. Rerun with -v to see more details.
Build completed unsuccessfully in 0:20:58
  local time: Sun Nov 16 14:55:52 UTC 2025
  network time: Sun, 16 Nov 2025 14:55:57 GMT
##[error]Process completed with exit code 1.
##[group]Run echo "disk usage:"

RalfJung · 2025-11-16T14:58:38Z

Fun, the cranelift backend has a whole bunch of cases of this. Cc @bjorn3

craterbot · 2025-11-17T15:58:42Z

🚧 Experiment pr-148952 is now running

ℹ️ Crater is a tool to run experiments across parts of the Rust ecosystem. Learn more

bjorn3 · 2025-11-17T18:55:00Z

Fun, the cranelift backend has a whole bunch of cases of this.

Would this work?

diff --git a/build_system/abi_cafe.rs b/build_system/abi_cafe.rs
index 5a393a21..762b2be8 100644
--- a/build_system/abi_cafe.rs
+++ b/build_system/abi_cafe.rs
@@ -11,7 +11,7 @@
     "abi-cafe",
 );
 
-static ABI_CAFE: CargoProject = CargoProject::new(&ABI_CAFE_REPO.source_dir(), "abi_cafe_target");
+static ABI_CAFE: CargoProject = CargoProject::new(ABI_CAFE_REPO.source_dir(), "abi_cafe_target");
 
 pub(crate) fn run(
     sysroot_kind: SysrootKind,
diff --git a/build_system/build_backend.rs b/build_system/build_backend.rs
index b9fa0ff2..ad6743a6 100644
--- a/build_system/build_backend.rs
+++ b/build_system/build_backend.rs
@@ -6,7 +6,7 @@
 use crate::shared_utils::{rustflags_from_env, rustflags_to_cmd_env};
 use crate::utils::{CargoProject, Compiler, LogGroup};
 
-static CG_CLIF: CargoProject = CargoProject::new(&RelPath::source("."), "cg_clif");
+static CG_CLIF: CargoProject = CargoProject::new(RelPath::source("."), "cg_clif");
 
 pub(crate) fn build_backend(
     dirs: &Dirs,
diff --git a/build_system/build_sysroot.rs b/build_system/build_sysroot.rs
index 70504ee8..804d50e2 100644
--- a/build_system/build_sysroot.rs
+++ b/build_system/build_sysroot.rs
@@ -140,7 +140,7 @@ fn install_into_sysroot(&self, sysroot: &Path) {
 
 static STDLIB_SRC: RelPath = RelPath::build("stdlib");
 static STANDARD_LIBRARY: CargoProject =
-    CargoProject::new(&RelPath::build("stdlib/library/sysroot"), "stdlib_target");
+    CargoProject::new(RelPath::build("stdlib/library/sysroot"), "stdlib_target");
 
 fn build_sysroot_for_triple(
     dirs: &Dirs,
diff --git a/build_system/tests.rs b/build_system/tests.rs
index dd8cf929..3b6a2e7a 100644
--- a/build_system/tests.rs
+++ b/build_system/tests.rs
@@ -129,7 +129,7 @@ const fn jit_bin(config: &'static str, source: &'static str, args: &'static str)
     "rand",
 );
 
-static RAND: CargoProject = CargoProject::new(&RAND_REPO.source_dir(), "rand_target");
+static RAND: CargoProject = CargoProject::new(RAND_REPO.source_dir(), "rand_target");
 
 pub(crate) static REGEX_REPO: GitRepo = GitRepo::github(
     "rust-lang",
@@ -139,15 +139,15 @@ const fn jit_bin(config: &'static str, source: &'static str, args: &'static str)
     "regex",
 );
 
-static REGEX: CargoProject = CargoProject::new(&REGEX_REPO.source_dir(), "regex_target");
+static REGEX: CargoProject = CargoProject::new(REGEX_REPO.source_dir(), "regex_target");
 
 static PORTABLE_SIMD_SRC: RelPath = RelPath::build("portable-simd");
 
-static PORTABLE_SIMD: CargoProject = CargoProject::new(&PORTABLE_SIMD_SRC, "portable-simd_target");
+static PORTABLE_SIMD: CargoProject = CargoProject::new(PORTABLE_SIMD_SRC, "portable-simd_target");
 
 static SYSROOT_TESTS_SRC: RelPath = RelPath::build("sysroot_tests");
 
-static SYSROOT_TESTS: CargoProject = CargoProject::new(&SYSROOT_TESTS_SRC, "sysroot_tests_target");
+static SYSROOT_TESTS: CargoProject = CargoProject::new(SYSROOT_TESTS_SRC, "sysroot_tests_target");
 
 const EXTENDED_SYSROOT_SUITE: &[TestCase] = &[
     TestCase::custom("test.rust-random/rand", &|runner| {
diff --git a/build_system/utils.rs b/build_system/utils.rs
index 3266aa0c..5c7cefa1 100644
--- a/build_system/utils.rs
+++ b/build_system/utils.rs
@@ -75,12 +75,12 @@ pub(crate) fn run_with_runner(&self, program: impl AsRef<OsStr>) -> Command {
 }
 
 pub(crate) struct CargoProject {
-    source: &'static RelPath,
+    source: RelPath,
     target: &'static str,
 }
 
 impl CargoProject {
-    pub(crate) const fn new(path: &'static RelPath, target: &'static str) -> CargoProject {
+    pub(crate) const fn new(path: RelPath, target: &'static str) -> CargoProject {
         CargoProject { source: path, target }
     }

Edit: Committed as rust-lang/rustc_codegen_cranelift@2017344

RalfJung · 2025-11-17T21:08:25Z

That should help, yeah. Alternatively, replacing &RelPath::source(".") by const { &RelPath::source(".") } would also work.

craterbot · 2025-11-19T09:50:04Z

🎉 Experiment pr-148952 is completed!
📊 6478 regressed and 5 fixed (737227 total)
📊 1826 spurious results on the retry-regessed-list.txt, consider a retry¹ if this is a significant amount.
📰 Open the summary report.

⚠️ If you notice any spurious failure please add them to the denylist!
ℹ️ Crater is a tool to run experiments across parts of the Rust ecosystem. Learn more

re-run the experiment with crates=https://crater-reports.s3.amazonaws.com/pr-148952/retry-regressed-list.txt ↩

RalfJung · 2025-11-19T19:49:43Z

We got the data, nothing left to do here.

crater experiment: do not promote function calls in const/static items

5f31375

rustbot added S-waiting-on-author Status: This is awaiting some action (such as code changes or more information) from the author. T-compiler Relevant to the compiler team, which will review and decide on the PR/issue. labels Nov 14, 2025

rust-bors bot added a commit that referenced this pull request Nov 14, 2025

Auto merge of #148952 - RalfJung:fn-call-promotion, r=<try>

943e220

crater experiment: do not promote function calls in const/static items

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RalfJung mentioned this pull request Nov 14, 2025

Bump some dependencies so owo-colors 3.x is gone oli-obk/ui_test#347

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craterbot added S-waiting-on-crater Status: Waiting on a crater run to be completed. and removed S-waiting-on-author Status: This is awaiting some action (such as code changes or more information) from the author. labels Nov 14, 2025

bump ui_test to remove old owo-colors

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craterbot added S-waiting-on-review Status: Awaiting review from the assignee but also interested parties. and removed S-waiting-on-crater Status: Waiting on a crater run to be completed. labels Nov 19, 2025

RalfJung closed this Nov 19, 2025

rustbot removed the S-waiting-on-review Status: Awaiting review from the assignee but also interested parties. label Nov 19, 2025

RalfJung mentioned this pull request Nov 19, 2025

Clean up implicit const promotion behavior #124328

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crater experiment: do not promote function calls in const/static items #148952

crater experiment: do not promote function calls in const/static items #148952

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